The long-term goal of the proposed research is to develop and test a set of experimental and analytical techniques for exploring (1) water flux and its effect on formed elements and macromolecules in pulsatile blood flow at arterial walls, (2) the way this water flux and the distribution of resistances to water flux plus the compliance of the arterial wall to the mobile water can contribute to the distribution of forces that will lead to the desquamation of endothelial cells in the presence of a pulse, and (3) the way vasoactive substances in the blood (as mediated by concentration polarization when it occurs) and physical factors such as arterial wall properties, mean pressure, and pulse height can influence the forces that lead to desquamation. The research will exploit a new research tool developed by FernandoVargas which employs an isolated arterial segment that permits the measurement of water flux and thresholds of endothelial cell desquamation caused by water flux. Computer and experimental flow chamber models will be employed to develop techniques for identifying pore sites in the endothelium and the volume rate of flow through these sites and their possible fluctuation with time.